A saponified ethylene-vinyl ester copolymer (EVOH resin) is used as a packaging film for foods and so on due to superior oxygen-barrier property. However, if the EVOH resin film is subjected to hot water treatment e.g. to retort treatment for a long time, particularly, the gas barrier property immediately after the hot water treatment may be lowered, the film may be whitened, or the shape retainability may be lowered.
A resin composition in which a desiccant is added to EVOH resin is known as a resin composition capable of obtaining a packaging film having excellent gas barrier property even after hot water treatment. For instance, U.S. Pat. No. 4,792,484 discloses a laminate film, wherein a resin composition obtained by dispersing fine particles of phosphate such as sodium phosphate as a desiccant in EVOH resin is used for an intermediate layer, and the intermediate layer is held between thermoplastic resin (e.g. polyethylene, polypropylene, or polyvinyl chloride) films. In the laminate film, the desiccant can absorb moisture intruded from film ends, or moisture transmitted through the thermoplastic resin film as an outer layer, and thereby the gas barrier property of EVOH resin can be prevented from lowering due to moisture.
Further, JP Sho 63-113062A discloses dispersing desiccant particles in an EVOH resin matrix in particulate state having an intended particle range. Examples of the desiccant include salts which absorb moisture in the form of crystallization water, hygroscopic compounds, and superabsorbent polymers. The publication describes a most preferred salt which absorbs moisture in the form of crystallization water is phosphate (anhydrous) such as monosodium phosphate, and other preferred examples of salts include sodium borate and sodium sulfate (see upper right column, page 3). The publication discloses an effect (gas barrier property) obtained, in the case where sodium pyrophosphate anhydrous, trisodium phosphate anhydrous, monosodium phosphate anhydrous, monosodium phosphate anhydrous, trilithium phosphate anhydrous, sodium borate anhydrous, sodium sulfate anhydrous, sodium nitrate, sodium chloride, or sugar is used as a desiccant. The publication describes that use of phosphate particularly shows excellent gas barrier property even after retort treatment for 120 minutes.    [Patent document 1] U.S. Pat. No. 4,792,484A    [Patent document 2] JP Sho63-113062A